The information set forth herein is furnished free of charge and is based on technical data that the AISE and the participating member companies

Transcription

1 The information set forth herein is furnished free of charge and is based on technical data that the AISE and the participating member companies believes to be reliable. It is intended for use by persons having technical skill and at their own discretion and risk. Since conditions of use are outside our control, we make no warranties, express or implied, and assume no liability in connection with any use of this information. Nothing herein is to be taken as a license to operate under or a recommendation to infringe any patents. 1

2 Welcometo the third webinar in the AISE Series on Enzyme Safety Management. This follows on from our initial introduction to Enzyme Safety, and previous webinar presented by Anthony Panepinto which discussed the steps you need to take to take in order to plan an effective risk management strategy for safe handling and manufacturing of products containing enzymes. In this session we will take a more practical look at some of the engineering control options that have been successfully employed by the detergent industry to control exposure to enzymes at source. 2

3 Our objectives todayare to consider what we actually mean by control of exposure to enzymes and we will look at some of the engineering options used to contain and control exposure to enzymes within the detergents industry. We will also look at the role of respiratory protection inour risk management strategy, and finally take a lookat a case study on product reclaim / rework a topic that is quite frequently overlooked by many companies. 3

4 Given that we have to handle enzymes-which we will discuss in a few moments -we can consider control of exposure to them, and to other materials that are hazardous by inhalation of dust or aerosol as a combination of several strategies; firstly we should prevent or minimise the formation of airborne dust or aerosol from raw materials or finished products, then we must containand/or remove any airborne dust or aerosol that might be produced by their handling or processing through a combination of engineering and ventilation control. From a process perspective we must avoid spillages of raw materials and products and in doing all of the above prevent personal exposure or reduce it below the limits that are considered safe. 4

5 We employ a strategy called the control hierarchy to decide on the control measures to employ; you may have heard of this already, it is relevant to virtually any safety strategy and there are various formats around with slightly different numbers of step's but the fundamental approach is to consider each level of the hierarchy in turn in order to Eliminate the Hazard, Prevent it s Release, or Protect People or Property from it should escape confinement. 5

6 For Industrial Hygienethere are 7 steps, beginning with the most effective control measure Elimination, working through the engineering control options, and finally as a last resort considering the use of personal and respiratory protection. The key point is that as we descend the control hierarchy the soltions become less effective. 6

7 Unfortunately we cannot Eliminate enzymes from our formulations, they providegreat benefit and there is no effective substitute. As we saw in our introductory session enzymes provide superior cleaning of surfaces, at low temperatures, they are non toxic, and completely biodegradable. We can however substitute their form, particularly powders, to make them less dusty and thereby reduce the risk of exposure; however even the modern enzyme encapsulates as low dust and robust as they are can not reduce the risk of exposure sufficiently and engineering controls are still an essential part of the risk management strategy. 7

8 Engineering controlsare based around isolating people from the raw material or products by using closed or sealed processes, providing partial enclosure and ventilation control for those processes or equipment that cannot be fully closedor sealed, and in some instances by using or incorporating local exhaust ventilation we will now consider these control options in turn, inmore detail, and illustrate the key features with some examples. 8

9 Isolation; essentially this is the use of fully closed or sealed equipment; designed so that dust or aerosol from raw materials or products cannot escape into the working environment during transfer or processing; we will look at some examples commonly used to discharge enzymes into processes, to blend formulations, and transfer raw materials and products between process stages. 9

10 In our first example the use of Dry break couplings for connection of liquid totes / IBC s to dosing equipment prevents spillage or aerosol release from either end of the coupling, and effects a safe transfer from the supply unit to the process. 10

11 Polythene lined big bags / super sacks can sealto a discharge station before being untied, resulting in a dust free transfer of enzyme encapsulates to the process. The liners can be removed by an automated system, or can be vacuum deflated prior to retying and removal from the outer big bag. 11

12 This is a more traditional type of big bag dischargestation, with a loose fitting bag that is not sealed onto or into the discharge opening -resulting in the release of dust and spillage of granules which can then be crushed under foot or by pallet trucks to release even more enzyme dust. 12

13 Control by isolation relies on well designed and well maintained plant and equipment; which in turn requires prompt reporting of defects; Lets look at a few more examples; 13

14 This is anencapsulates dosing station; so the big bag we saw earlier might feed enzymes directly into the small hopper. A short belt within the closed system doses enzymes continually onto a post dosing belt or into a batch process via closed the outlet. Any air that is displaced from the unit into the workplace by the material flow passes through a HEPA filter to remove dust. [High Efficiency Particle Arrestor]. This is a good example of a closed/sealed dosing unit. 14

15 Here is a poor example of a weigh belt, the enclosure is damaged, the panels do not fit correctly, the transparentpanels are cracked leading to loss of containment / release of dust. 15

16 Drum mixing either continuous or batch mixing is commonly used to blend detergent powders. This is a great example; closed, well maintained, clean, no spillage, no dust release the containment is so good that you cannot tell what it is blending just by looking at it. 16

17 This is a bad example of the same process it is clear that there are many faults with this equipment leading to gross contamination and significant release of dust. 17

18 To Recap; Isolation depends on well designed equipment, well maintained. If you can see spillage or dust then isolation as a control strategy is not working and you may need to fix it or supplement it with ventilation control. 18

19 Someprocesses cannot be fully isolated; or regular access is required for some reason, in which case we need to enclose the process as much as is practical and then provide ventilation control [extraction] to ensure that at any remaining gaps or openings in the enclosure air is always moving inwards at a high enough velocity to stop dust or aerosol coming out into the workplace! 19

20 Typicallythis strategy is applied to packing machines, some mixing vessels, belt conveyors, and product reclaim booths. To achieve effective control the inward air velocity at any gap or opening must be >= 1.0m/s. Similarly across the open face of a productrework booth the average air velocity must be >=1.0m/s, but it must be uniform across the face, so no single point of measurement must deviate by more that +/-10% from the average. This is the industry standard We will discuss this more when we consider rework booths 20

21 This is a big bag / super sack dump station; we saw one before that was poorly designed this is a goodexample; it is designed to capture any spillage from the empty big bag, the stations are well ventilated to contain dust, and the whole room is under negative pressure as a safeguard if there is any accidental release / spillage within the room. An operator working in this room, discharging bags, would be expected to wear respiratory protection as a safeguard to protect against high peak exposures in the event of an incident we will return to the use of respiratory protection a little later. 21

22 This is a liquids packing machine; note the full enclosure including the headertank and the small entry and exit openings for packaging It is maintained under negative pressure and meeting the >=1.0m/ standard. Note also the bunding on the floor in case of major leaks/spills/failures. The ventilation control on this particular enclosure is linked to the operation of the filler; if the ventilation is not working the filler cannot operate. The doors are also interlocked and cannot be opened until a time delay has passed to allow the ventilation to clear any airborne aerosol that may be present withinthe enclosure before the doors are opened. 22

23 Belt conveyors must also be enclosed and ventilated; the return belt underneath the conveyor can often present problems -as you can see in this picture. If you see temporary fixes / powder spillages then act on them and put them right do not live with them!! 23

24 Enclosure and ventilation requirescareful design to work effectively; it is important to understand how the air circulates within a process enclosure; you can force air to travel in a certain way and increase effectiveness of ventilation if you plan it correctly. It is also important to fit static pressure gauges to ventilated equipment, with clearly marked working pressures, so that the performance can be checked by anyone at any time. 24

25 Static pressure gauges come in many formats; they are inexpensive, require no power, are simple to install, and can provide direct confirmation that ventilation control is operating as it should if installed,marked correctly, and validated against the ventilation design. 25

26 Sometimes enclosure and ventilation might seem an impossible task, due to complexity of equipment, space, cost etc. Sometimes Local Exhaust ventilation [LEV] appears to be the cheapest or easiest option. 26

27 LEV is typically found in engineering workshops or material dispensaries. To work it has to be positioned correctly and very veryclose to the source of the contaminant to work properly. It is not normally used for very hazardous materials as we will see 27

28 There are many factors that determine the efficiency of LEV; getting any one of these wrong, or installing it in the wrong place, can cause it to fail. LEV is not considered suitable on its own for control of exposure to enzymes from raw materials, intermediates or finished products. 28

29 The example demonstrates that LEV alone is not very efficient and as we discussed already it is very easy to misuse and to lose control! That is why we do not rely on LEV for control of exposure to enzymes or products that contain them. LEV is more suited to materials of lower hazard 29

30 Just to compete the picture on LEV The position of LEV is important; it must pull the contaminant way from the operator; and the contaminant must be released within the capture zone of the LEV if not then it will not work. If the LEV is abovethe sourceof dust then it ensures that the operator gets exposed it pulls dust/aerosol right through the breathing zone; if you have LEV fitted this way at a workstation to try and control dust or aerosol then you should change it immediately. 30

31 LEV can be used insideenclosures such as packing machines to supplement the ventilation provided to the enclosure, capture point sources of emission, keeps the enclosure clean, and contribute to the overall performance. 31

32 A final word about controls; itmight seem obvious but if they are not used properly then they will not work. Operators must use the controls provided to protect themselves and their co-workers. In this example the IBC cleaning station is designed to be a closed CIP system,the cap and CIP nozzle should be screwed on to the top of the IBC, but the operator is using the CIP system like a hosepipe to make the job quicker; as a result he is exposing himself and others to enzyme product aerosol that is expelled from the open top of the IBC as it fills with water. For this type of activity a high level of enzyme aerosol, well above the Occupational Exposure Guidance Limit, is frequently measured. 32

33 We have mentioned respiratoryprotection several times; RPE is a defence it is not a control measure. RPE minimises exposure after it has already occurred. Generally good quality dust masks can offer up to a 20x reduction for an airborne particulate contaminant, but rarely is that obtained in practice. 33

34 It s efficiency is generally poor and depends upon the face fit to the person. If a man is not clean shaven then the face seal will be poor and the efficiency of the mask will be low. For a lady if a small size mask is not available then the standard size may be too big and leave gaps around the siders again reducing the performance. RPE seldom achieves its APF, and is not suitable for enzymes other than secondary protection in addition to control measures, for short term activities such as cleaning spillages, or in the case of an emergency. All operators required to use respiratory protection must be fully trained to do so, and must undergo face fit testing for the type that they are asked to use. 34

35 Reclaimingproduct from packs for rework / repacking can expose operators to dust and aerosol containing enzyme. Even the dust or aerosol from products containing less than 1% enzyme can contain a significant amount of protein and result in exposures in excess of the occupational exposure guidance limits. It is often thought that the dilution of enzyme in a finished product renders the product non hazardous with respect to enzymes that is not the case. 35

36 Reclaim/rework is a high risk task, more often thannot it is a fully manual rip and tip operation for powders, or pouring operation for liquids. There is close interface between the operator and the task hence a high risk of exposure to dust or aerosol. In our introductory session it was emphasised that even a very low airborne concentration of airborne dust or aerosol from finished products can contain a very significant quantity of enzyme protein sufficient to exceed the exposure limits. 36

37 This reclaim booth is a poor design; the ventilation extract point is positioned incorrectly, air will short circuitinto the top of the booth, and there is no airflow where the operator is opening packs. The waste bin is behind the operator empty packs are pulled out of the booth and through his breathing zone, and powder is collected in a bin underneath which requires additional handling. 37

38 A properly designed booth is illustrated here; the face velocity is uniform as a result of the extraction being positioned at the back of the booth at threelevels; reclaimed powder [or liquid] is diverted direct to the process [or a day bin/silo]; and the packaging is posted through a slot at the back [or side] of the booth into a waste sack. The process is in a single direction as is the airflow Nothing is withdrawn from the booth through the operators breathing zone 38

39 This is a real example a horizontal laminar flow rework booth Note that the risk of short duration peak exposures from handling damaged / open packs, or if spillages occu,ris still high and therefore respiratory protection is always required for this type of task 39

40 That brings us to the end of this session; it is not possible to cover every conceivable process / task in such a short time but hopefully what is contained hereprovides a good baseline. In addition the latest AISE guidance document GUIDELINES FOR THE SAFE HANDLING OF ENZYMES IN DETERGENT MANUFACTURING 2015 is available from the AISE web site. 40

41 There is also some good free guidance on ventilation design available from UK HSE and some examples from laundry processes in the 28 th edition of the ACGIH Industrial Ventilation Manual 41

42 Thank you for attending today and I hope that you will join some or all of our future webinars. 42

43 Thank you for attending today and I hope that you will join some or all of our future webinars. 43